[TowerTalk] A near imminent TX-455 failure

[K8RI on Tower talk]

I was going to say the same thing about the welds and although the photos 
are a tad small and low in contrast they sure look like inadequate 
penetration.  The photo that is the third from the last sure looks like what 
I'd expect.


> >From the photographs, it appears that failure originated from the edge of
> the weld beads. Usually this indicates lack of fusion on the weldments.
> Failure should occur in the base metal.  It also appears that the tower is
> either painted or galvanized (I can't tell because I can't see well enough
> at the fracture.  Since the welds appear to have failed at the weld bead,
> grinding the weld bead off, then rewelding would be appropriate.  I would
> also suggest some sort of backing plate to reduce the loads on the weld 
> may
> be utilized to reduce the stresses on the weldment.  The hard part will be
> getting the  joints lined up for welding.

For the round stuff a couple of "C-Clamps" used with the proper size angle 
iron and a bit of imagination should do well.  I've welded a bunch like 
that.  The problem with tube to plate welds is there is very little 
difference between inadequate penetration and blowing a hole through the 
tube.  It's a job for a good MIG or TIG welder.

Although it might cost a bit there are probably certified welders in your 
area with portable, gas powered rigs that could come out and to the job in 
place (if they can get at it.) or they might tack it suficiently to allow 
taking the tower down so a proper job could be done.  That's a pretty 
straight forward job once you can get at it.

Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
www.rogerhalstead.com

>
> In my former life doing failure analysis on structures and components,
> unfortunately, this is a common mode of failure, most often associated 
> with
> inadequate penetration of the weld.
>
> IMHO
>
> Scott aka KBOFHP
>
>
> -----Original Message-----
> From: towertalk-bounces at contesting.com
> [mailto:towertalk-bounces at contesting.com]On Behalf Of Nick - VE3EY
> Sent: Sunday, November 13, 2005 8:26 PM
> To: towertalk at contesting.com
> Subject: [TowerTalk] A near iminent TX-455 failure
>
>
> I am posting this note on behalf of a friend of mine.
>
> His 55 foot TX-455 US Tower is on the verge of collapsing down.  The
> owner just noticed that two out of three legs of his tower just broke
> down.   The legs snapped just above the mounting ears where the tower is
> fastened to the "T" mounting plate.   We suspect that some 90 km/h wind
> gusts we have had here in Toronto last week may have been a contributing
> factor.
>
> The tower is currently nested and the antennas are still on top of it.
> It is basically holding on only one of the remaining legs and a few
> cross braces.   It was installed brand new in 1990 and it had a 2 el GEM
> Qubical Quad installed ever since.   In 2003, owner replaced the short
> mast with a 22" cromoly nested about 3" inside the tower and added a
> home made rotary dipole for 30/40 m at about 10 feet above the Gem
> Quad.   The dipole is a modified Cushcraft D3W warc dipole.
>
> The pictures of the damage can be seen here. 
> http://dx.fireroute.com/TX455
>
> We are looking for some advice how to remedy this problem.   Would there
> be any way to fix this tower short of buying a new one?
>
>
> 73,  Nick
> ve3ey
>
>
> _______________________________________________
>
> See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
> Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with 
> any
> questions and ask for Sherman, W2FLA.
>
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> _______________________________________________
>
> See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless 
> Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with 
> any questions and ask for Sherman, W2FLA.
>
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